The present invention relates to a multi-chip module (MCM) in which a plurality of bare IC chips are mounted on a printed wiring board.
As the decrease in size and the enhancement in performance of electronic equipment are required. integrated circuits (ICs) mounted on a printed wiring board 1 as shown in FIG., 1 have been evolving from package-type ICs 2 to bare IC chips 3 shown in FIG. 2, and further to multi-chip modules 5 as shown in FIG. 3.
In an arrangement shown in FIG. 2. bare IC chips 3 are mounted directly on a printed wiring board 1 by means of die bonding and wire bonding. The areas of the printed wiring board required for mounting the bare IC chips are smaller as compared with a case in which package-type ICs 2 covered with armoring material such as plastic or ceramics are mounted on the printing wiring board 1. However, if after mounting a lot of bare ICs chips 3 on a printed wiring board 1, any of the bare ICs chips 3 is found to be defective, the board 1 itself is scrapped because it is difficult and troublesome to remove the defective bare IC chip from the board 1 (to repair the board 1). In other words, there is a problem that the manufacturing process results in a poor yield.
A multi-chip module 5 which solves the above problem is shown in FIG. 3. Referring to FIGS. 4 and 5, the manufacturing process of this multi-chip module 5 is briefly described. In the process, bare IC chips 52 are fixed by die bonding on a multilayer printed wiring board 51, and the electrical connections are achieved by wire bonding. Each bare IC chip is fit with a dam frame, and sealed with resin. Then, lead terminals 55 of the Gull Wing Type are soldered as outer electrodes to the electrode pads provided on the peripheral regions of the printed wiring board 51, thus completing the multi-chip module 5.
Since in case of multi-chip modules 5, each multi-chip module can be tested alone in the operation, only the multi-chip modules 5 which have been passed the test can be mounted on a printed wiring board such as a mother board (hereinafter, a printed wiring board on which multi-chip modules are to be mounted is referred to as a xe2x80x9ctarget printed wiring boardxe2x80x9d).
However, there are following problems in these conventional multi-chip modules. First, a lot of lead terminals 55 have to be soldered to the periphery of the printed wiring board 51. For this, the number of working processes increases, and the packaging density on a target printed wiring board 1 is reduced by the areas on the target printed wiring board 1 which are occupied by the lead terminals 55.
In the second place, the size of the printed wiring board 51 becomes larger as compared with the size of bare IC chips mounted on the printed wiring board 51 because a circuit pattern (not shown) for electrically interconnecting a plurality of bare IC chips 52 has to be provided around the bare IC chips 52.
In the third place, in such an arrangement that each bare IC chip 52 is fit with a dam frame 53 for sealing with resin 57, large areas are occupied by the dam frames 53 so attached as to enclose the respective bare IC chips 52. This also causes the size of the printed wiring board 51 to become large.
Also, the dam frames 53 are glued to the printed wiring board 51 by inserting projections 53a provided on each dam frame 53 into holes 51a of the printed wiring board 51 for positioning. Accordingly, the printed wiring board 51 is provided with a lot of positioning holes 51a, which make the circuit pattern complicated and cause the size of the printed wiring board 51 to become large.
Further, if sections of a multi-chip module 5 which have been enclosed by dam frames 53 are to be absorbed by a vacuum absorber 7 in mounting the multi-chip module 5 on a target printed wiring board 1, enough absorption area can not be obtained because of the small size of each dam frame 53. Thus, the absorbing and holding of multi-chip module is difficult, and operations tend to be unstable.
In the fourth place, if resistors and capacitors for adjusting the circuit are provided for a multi-chip module to form a compound module, then around the bare IC chips 52 there have to be extra areas where chip resistor elements, chip capacitor elements and electrode pads to which they are soldered are disposed. This also cause the size of the printed wiring board 51 to become large. And, since the chip elements have to be soldered after sealing the bare IC chips with resin, the number of working processes increase.
On the other hand, if the chip resistor and capacitor elements are mounted on the printed wiring board on which the multi-chip module 5 is mounted, the area for mounting the module 5 including the chip elements increases, causing the size of the target printed wiring board to become large.
As described above, in conventional multi-chip module: the number of attaching processes of the lead terminals; the size becomes larger in accordance with the number of the lead terminals; the printed wiring board increases in size because of a circuit pattern for interconnecting the bare IC chips; the number of processes of attaching dam frames to the bare IC chips; the attaching of dam frames causes the size of the printed wiring board; it is difficult to vacuum-absorbing dam frame sections for mounting the multi-chip module to the target printed wiring board.
There is also another problem that if resistors and capacitors for adjusting the circuit are provided for a multi-chip module to form a compound module, then the size of the multi-chip module becomes large, thereby increasing the size of the printed wiring board on which the multi-chip module is mounted.
The present invention is intended for solving these and other problems and disadvantages of the prior art. An object of the invention is to providing a multi-chip module which can be made smaller than a conventional one, which can be manufactured in a reduced number of process. and which can be easily mounted to a target printed wiring board by means of vacuum absorption.
Solution
A multi-chip module according to a first aspect of the invention comprises a printed wiring board (100) and a plurality of bare IC chips (201 through 203), is mounted on a target printed wiring board (1), and is characterized by outer electrode pads (105) disposed along the peripheral portion of the printed wiring board, each having a geometry in which cutting a through hole longitudinally into halves results, the outer electrode pads being to be soldered to the target printed wiring board.
A multi-chip module according to a second aspect of the invention comprises a printed wiring board (100) and a plurality of bare IC chips (201 through 203), is mounted on a target printed wiring board (1), and is so arranged that: a circuit pattern is provided on each of at least one of the areas of the printed wiring board on which the plurality of bare IC chips are mounted; and an insulating layer is provided on each of the circuit patterns.
A multi-chip module according to a third aspect of the invention is so arranged that: a circuit pattern is provided on each of at least one of the areas of the printed wiring board on which the plurality of bare IC chips are mounted; and an insulating layer is provided on each of the circuit patterns.
A multi-chip module according to a fourth aspect of the invention comprises a printed wiring board (100) and a plurality of bare IC chips (201 through 203), is mounted on a target printed wiring board (1), and is so arranged that: at least one of a printed resistor element and a printed dielectric is provided on each of at least one of the areas of the printed wiring board on which the plurality of bare IC chips are mounted; and an insulating layer is provided on each of the at least one of the printed resistor element and the printed dielectric.
A multi-chip module according to a fifth aspect of the invention is so arranged that: at least one of a printed resistor element and a printed dielectric is provided on each of at least one of the areas of the printed wiring board on which the plurality of bare IC chips are mounted; and an insulating layer is provided on each of the at least one of the printed resistor element and the printed dielectric.
A multi-chip module according to a sixth aspect of the invention comprises a printed wiring board (100) and a plurality of bare IC chips (201 through 203) mounted on the printed wiring board, is to be mounted on a target printed wiring board (1), and is so arranged that: the printed wiring board has a multilayer structure: the printed wiring board is provided with inner conductor layers within the multilayer structure and connecting portions such as interstitial via holes leading from the bare IC chip mounting side to the inner conductor layers; and the bare IC chips are electrically interconnected via the interstitial via holes and the inner conductor layers.
A multi-chip module according to a seventh aspect of the invention is so arranged that: the printed wiring board has a multilayer structure; the printed wiring board being provided with inner conductor layers within the multilayer structure and interstitial via holes leading from the bare IC chip mounting side to the inner conductor layers; and the bare IC chips are electrically interconnected via the interstitial via holes and the inner conductor layers.
A multi-chip module according to an eighth aspect of the invention comprises a printed wiring board (100) and a plurality of bare IC chips (201 through 203), is mounted on a target printed wiring board (1), and is so arranged that: the printed wiring board has a multilayer structure; and within the multilayer structure, there are provided at least one resistor element both the ends of which are electrically connected to inner conductor layers within the multilayer structure.
A multi-chip module according to a ninth aspect of the invention is so arranged that: the printed wiring board has a multilayer structure; and within the multilayer structure, there are provided at least one resistor element both the ends of which are electrically connected to inner conductor layers within the multilayer structure.
A multi-chip module according to a tenth aspect of the invention comprises a printed wiring board (100) and a plurality of bare IC chips (201 through 203), is mounted on a target printed wiring board (1), and is so arranged that: the printed wiring board has a multilayer structure; and within the multilayer structure, there are provided at least one dielectric layer both the sides of which are electrically connected to inner conductor layers within the multilayer structure.
A multi-chip module according to an eleventh aspect of the invention is so arranged that: the printed wiring board has a multilayer structure; and within the multi layer structure, there are provided at least one dielectric layer both the sides of which are electrically connected to inner conductor layers within the multilayer structure.
A multi-chip module according to a twelfth aspect of the invention comprises a printed wiring board (100) and a plurality of bare IC chips (201 through 203), is mounted on a target printed wiring board (1), and is so arranged that: the printed wiring board has a multilayer structure; and within the multilayer structure, there are provided at least one resistor element both the ends of which are electrically connected to inner conductor layers within the multilayer structure and at least one dielectric layer both the sides of which are electrically connected to inner conductor layers within the multilayer structure.
A multi-chip module according to a thirteenth aspect of the invention is so arranged that: the printed wiring board has a multilayer structure; and within the multilayer structure, there are provided at least one resistor element both the ends of which are electrically connected to inner conductor layers within the multilayer structure and at least one dielectric layer both the sides of which are electrically connected to inner conductor layers within the multilayer structure.
A multi-chip module according to a fourteenth aspect of the invention is so arranged that at least one of a printed resistor element and a printed dielectric permitting trimming for adjustment is provided outside the areas on the surface of the printed wiring board on which the plurality of bare IC chips are mounted.
A multi-chip module according to a fifteenth aspect of the invention comprises a printed wiring board (100) and a plurality of bare IC chips (201 through 203), is mounted on a target printed wiring board (1), and is characterized by a dam frame so provided on the printed wiring board as to enclose the plurality of bare IC chips, the inside of the dam frame being filled with resin for sealing the bare IC chips.
A multi-chip module according to a sixteenth aspect of the invention is characterized by a dam frame so provided on the printed wiring board as to enclose the plurality of bare IC chips, the dam frame being filled with resin for sealing the bare IC chips.
A multi-chip module according to a seventeenth aspect of the invention is so arranged that the dam frame is provided with a reinforcing part railing between two of the bare IC chips.
A multi-chip module according to an eighteenth aspect of the invention is so arranged that chip electrode pads are disposed on the periphery of the bare IC chips on the bare IC chip mounting side of the printed wiring board, so that the boundary between the chip electrode pads and the surrounding area of them serves as reference for positioning of the dam frame when the dam frame is mounted.
A multi-chip module according to a nineteenth aspect of the invention is so arranged that chip electrode pads are disposed on the periphery of the bare IC chips on the bare IC chip mounting side of the printed wiring board, and a solder resist is provided adjacent to the chip electrode pads. so that the boundary between the chip electrode pads and the solder resist serves as reference for positioning of the dam frame when the dam frame is mounted.
A multi-chip module according to a twentieth aspect of the invention is so arranged that the dam frame is filled with resin for sealing the bare IC chips so that the surface of the resin is not higher than the upper face of the dam frame.
A multi-chip module according to a twenty-first aspect of the invention is so arranged that the bare IC chips are mounted on the printed wiring board by means of flip chip bonding.
A multi-chip module according to a twenty-second aspect of the invention comprises a printed wiring board (100) and a plurality of bare IC chips (201 through 203), is mounted on a target printed wiring board (1), and is characterized by through holes provided on the margin of the printed wiring board as outer electrode pads which are to be soldered to the mother board.
A multi-chip module according to a twenty-third aspect of the invention comprises a printed wiring board (100) and a plurality of bare IC chips (201 through 203), is mounted on a target printed wiring board (1), and is characterized by outer electrode pads which are to be soldered to the mother board, each pad extending from a point on the margin of the printed wiring board and across the end face of the printed wiring board.
A multi-chip module according to a twenty-fourth aspect of the invention is so arranged that the outer electrode pads are soldered to lands of the target printed wiring board with the multi-chip module face to face with or perpendicular to the target printed wiring board.
A multi-chip module according to a twenty-fifth aspect of the invention is so arranged that after mounting the bare IC chips within the dam frame and sealing the bare IC chips by filling the dam frame with resin, other bare IC chips are disposed on the dam frame and the resin.
A multi-chip module according to a twenty-sixth aspect of the invention is so arranged that: the printed wiring board is provided with through holes or concavities in which the bare IC chips are disposed; and the bare IC chips are disposed in the through holes or concavities and connected by means of wire bonding.
A multi-chip module according to a twenty-seventh aspect of the invention is so arranged that the target printed wiring board is provided with a through hole; the multi-chip module is disposed in the through hole; and the external electrode pads of the multi-chip module are soldered to lands of the target printed wiring board.
A multi-chip module according to a twenty-eighth aspect of the invention is so arranged that the bare IC chips are directly connected to the outer electrode pads by means of wire bonding.
A multi-chip module according to a twenty-ninth aspect of the invention is so arranged that a printed conductor which serves as an inductance for processing a high frequency signal is formed together with the at least one of a printed resistor element and a printed dielectric.
A multi-chip module according to a thirtieth aspect of the invention is so arranged that a flexible printed wiring board is used as a target printed wiring board on which the multi-chip module is mounted.
A multi-chip module according to a thirty-first aspect of the invention is so arranged that a dam frame is formed of a metal member and the bare IC chips are sealed with heat conductive resin so as to facilitate heat radiation from the bare IC chips.
A multi-chip module according to a thirty-second aspect of the invention is so arranged that a dam frame is formed of a metal member in such a shape that the top of the dam frame is extend to cover the bare IC chips, and the bare IC chips are sealed with heat conductive resin so as to facilitate heat radiation from the bare IC chips.
A multi-chip module according to a thirty-third aspect of the invention is characterized by a conductive cover for shielding the bare IC chips disposed on the printed wiring board from electromagnetic field.
A multi-chip module according to a thirty-fourth aspect of the invention is further characterized by a conductive cover for shielding the multi-chip module disposed on the target printed wiring board from electromagnetic field.
A multi-chip module according to a thirty-fifth aspect of the invention is characterized in that the printed wiring board of the multilayer structure is formed of ceramic material, glass epoxy material, and/or resin material.
Advantageous Effects
In a multi-chip module according to any of the 1st, 5th, 7th, 9th, 11th, 12th, 16th, 22nd, 23rd and 28th aspects of the invention, the geometry of each outer electrode pad which cutting a through hole in the longitudinal direction yields for soldering the multi-chip module to the target printed wiring board, outer electrode pads each comprising a through hole provided on the margin, outer electrode pads extending from the margin and across the end face, or the direct connection between the bare IC chips and the outer electrode pads by means of wire bonding eliminates the need of providing the margin of the printed wiring board with lead terminals as is done in conventional multi-chip modules.
In a multi-chip module according to any of the 2nd, 5th, 7th, 9th, 11th, 12th and 16th aspects of the invention, a circuit pattern is disposed in areas on the printed wiring board where bare IC chips are mounted, resulting in a reduction of the circuit pattern which is to be provided around the bare IC chips.
In a multi-chip module according to any of the 3rd, 5th, 7th, 9th, 11th, 12th and 16th aspects of the invention, the circuit pattern which is to be provided around the bare IC chips is reduced because there is no need for providing the lead terminals as in the multi-chip modules of the 1st or 2nd aspect of the invention.
In a multi-chip module according to any of the 4th, 5th, 7th, 9th, 11th, 12th, 16th and 29th aspects of the invention, there is no need for providing chip resistor elements, chip capacitors or inductors around the bare IC chips because resistor elements, capacitors and inductors can be formed on the areas, on the printed wiring board, where the bare IC chips are mounted.
In a multi-chip module according to any of the 6th, 7th, 9th, 11th, 12th, 16th and 35th aspects of the invention, the bare IC chips are electrically interconnected via interstitial via holes and inner conductor layers provided within a multilayer structure formed of ceramic material, glass epoxy material, and/or resin material. Accordingly, the circuit pattern which has to be provided around the bare IC chips is reduced.
In a multi-chip module according to any of the 8th, 9th and 16th aspects of the invention, since resistor elements can be formed within the printed wiring board, there is no need for providing chip resistor elements on the surface of the printed wiring board.
In a multi-chip module according to any of the 10th, 11th and 16th aspects of the invention, since capacitors can be formed within the printed wiring board, there is no need for providing chip capacitors on the surface of the printed wiring board.
In a multi-chip module according to any of the 12th, 13th and 16th aspects of the invention, since resistor elements, capacitors, and inductors are formed within the printed wiring board, there is no need for providing chip resistor elements, chip capacitors, and inductors on the surface of the printed wiring board.
In a multi-chip module according to any of the 14th, 16th and 29th aspects of the invention, there is provided printed resistor elements, printed dielectrics and printed inductors, which has effects of not only any of the 1st through 13th aspects of the invention but also permitting a fine adjustment of operational characteristics of the circuit by removing a part of the printed resistor elements, the printed dielectrics and the printed inductors.
In a multi-chip module according to any of the 15th, 16th and 25th aspects of the invention, since a single dam frame encloses a plurality of bare IC chips, there is no need for providing each bare IC chip with a dam frame.
A multi-chip module according to the 17th aspect of the invention has not only the effect of 15th or 16th aspect of the invention but also the effect of reducing a strain caused by heat at the time of resin sealing and reflow soldering because the dam frame is provided with a reinforcing part.
Since in a multi-chip module according to the 18th aspect of the invention the dam frame is mounted on the printed wiring board being positioned on the basis of the boundary between the electrode pads and the surrounding area, there is no need for providing the printed wiring board with holes in which the dam frames are mounted, as in case of the 15th through 17th aspects of the invention.
In a multi-chip module according to the 19th aspect of the invention, the boundary between the electrode pads (e.g., golden color) and solder resist (e.g., green) provided adjacently to the electrode pads for preventing the solder from bridging electrode pads is used as a reference position for dam frame mounting. The color difference makes the boundary more clear.
In a multi-chip module according to the 20th aspect of the invention, since the surface of the resin filling the dam frame enclosing a plurality of bare IC chips is not higher than the dam frame, the area enclosed by the dam frame can be easily absorbed by a vacuum absorber.
In a multi-chip module according to the 21st aspect of the invention, since the bare IC chips are mounted on the printed wiring board by means of flip chip bonding, there is no need for disposing bonding pads around the bare IC chips on the surface of the printed wiring board.
In a multi-chip module according to the 24th aspect of the invention, there is a degree of freedom of the way of mounting the multi-chip module in that the multi-chip module may be disposed in parallel or perpendicular to a target printed wiring board.
In a multi-chip module according to the 25th aspect of the invention, after mounting the bare IC chips within the dam frame and sealing the bare IC chips by filling the dam frame with resin, other bare IC chips are disposed on the dam frame and the resin. Accordingly, a larger number of bare IC chips can be disposed on the multi-chip module.
In a multi-chip module according to the 26th or 27th aspect of the invention, the bare IC chips are disposed in holes or concavities of a target printed wiring board and connected to the board by means of wire bonding, or the multi-chip module is inserted in a hole of a target printed wiring board. Therefore, the total thickness is kept thin.
In a multi-chip module according to the 30th aspect of the invention, the multi-chip module is disposed on a flexible wiring board, which enables three-dimensional disposition.
In a multi-chip module according to the 31th or 32th aspect of the invention, the sealing is achieved with a metal dam frame and heat-conductive resin. and accordingly the heat radiation from the bare IC chips is ensured.
In a multi-chip module according to the 33th or 34th aspect of the invention, the bare IC chips or the multi-chip module are covered with a conductive cover preventing electrodes from being short-circuited, and are shielded from electromagnetic field.